JP7629390B2 - Welding torch - Google Patents

Description

The present invention relates to a welding torch.

In welding (TIG welding and plasma welding) using a welding torch equipped with a non-consumable electrode, an arc is generated between the electrode (non-consumable electrode) made of tungsten and the workpiece, and the heat of the arc melts the workpiece. In TIG welding, shielding gas is flowed between the gas nozzle and the electrode. In plasma welding, in addition to the shielding gas, plasma gas is flowed inside the insert tip placed around the electrode to restrain the arc (plasma arc). As a result, a highly concentrated high-temperature plasma flow is generated, and the stored energy is used to perform welding.

When welding metals with a relatively low melting point (low melting metals) such as zinc-plated steel sheets, zinc vapor and fumes are generated by the welding heat. If metals such as fumes adhere to the electrode, the arc generated during welding becomes unstable. In TIG welding, the tip of the electrode usually protrudes from the tip of the nozzle, and if the tip of the electrode is covered with metals such as fumes, there is a risk of poor ignition at the start of welding. In plasma welding, the tip of the electrode is usually retracted from the tip of the insert tip that surrounds the electrode. In addition, plasma gas is flowed inside the insert tip (around the electrode). For this reason, when welding low melting metals such as zinc-plated steel sheets, metals such as fumes are less likely to adhere to the electrode in plasma welding than in TIG welding. On the other hand, in plasma welding, metals such as fumes may adhere to the tip of the insert tip, which then becomes alloyed with the tip of the insert tip. This alloying of the tip of the insert tip may cause poor arcing or poor welding.

Patent Document 1 discloses a configuration in which multiple side plasma gas ejection holes made of small diameter holes are provided around the plasma gas ejection hole at the tip of the insert tip. By providing these multiple side plasma gas ejection holes, it is possible to reduce the adhesion of fumes and the like to the tip of the insert tip during welding. However, the structure described in Patent Document 1 makes the insert tip structure complex and leads to an increase in the size of the tip of the insert tip (welding torch). In addition, if the axis of the insert tip, which is arranged with a gap around the electrode, is offset from the axis of the electrode, there is a risk that the plasma gas ejected from the tip of the insert tip will drift, resulting in a decrease in welding quality.

JP 2009-172644 A

The present invention was conceived under these circumstances, and its main objective is to provide a welding torch that is suitable for welding low-melting metals while simplifying the structure and miniaturizing the tip.

To solve the above problems, the present invention employs the following technical means:

The welding torch provided by the first aspect of the present invention comprises a non-consumable electrode extending in the axial direction, a cylindrical first member arranged radially outside the non-consumable electrode, an inner nozzle arranged radially outside the non-consumable electrode and on one side of the first member in the axial direction, a locking member that is fitted across a first end of the first member on one side of the axial direction and a second end of the inner nozzle on the other side of the axial direction and that locks to both the first member and the inner nozzle, and a locking member arranged radially outside the inner nozzle. and an electrode centering member arranged radially outside the non-consumable electrode and radially inside the inner nozzle, the electrode centering member is concentrically fitted around the non-consumable electrode, and the inner nozzle is concentrically fitted around the electrode centering member, a first gas flow path for flowing a first inert gas is formed between the non-consumable electrode and the inner nozzle, and a second gas flow path for flowing a second inert gas is formed between the inner nozzle and the outer nozzle.

In a preferred embodiment, the locking member and the first end of the first member are connected by a screw.

In a preferred embodiment, the system has a first gas inlet that communicates with the first gas flow path and a second gas inlet that communicates with the second gas flow path, and the flow rate of the first inert gas introduced into the first gas inlet and the flow rate of the second inert gas introduced into the second gas inlet are each adjusted separately.

In a preferred embodiment, the first inert gas and the second inert gas are both at least one gas selected from argon gas and helium gas.

In a preferred embodiment, the first minimum gap, which is the smallest gap between the non-consumable electrode and the inner nozzle in the first gas flow path, is 0.2 to 0.5 times the second minimum gap, which is the smallest gap between the inner nozzle and the outer nozzle in the second gas flow path.

A welding system provided by a second aspect of the present invention includes a welding torch according to the first aspect of the present invention, a gas supply source communicating with both the first gas flow path and the second gas flow path, a first gas adjustment unit interposed between the gas supply source and the first gas flow path and adjusting the amount of the first inert gas flowing through the first gas flow path, and a second gas adjustment unit interposed between the gas supply source and the second gas flow path and adjusting the amount of the second inert gas flowing through the second gas flow path.

A welding system provided by a third aspect of the present invention includes a welding torch according to the first aspect of the present invention, a first gas supply source communicating with the first gas flow passage, a second gas supply source communicating with the second gas flow passage, a first gas adjustment unit interposed between the first gas supply source and the first gas flow passage and adjusting the amount of the first inert gas flowing through the first gas flow passage, and a second gas adjustment unit interposed between the second gas supply source and the second gas flow passage and adjusting the amount of the second inert gas flowing through the second gas flow passage.

The welding torch according to the present invention includes an electrode centering member and a locking member. The electrode centering member is concentrically fitted around the non-consumable electrode and is also concentrically fitted around the inner nozzle electrode centering member. As a result, the inner nozzle is arranged concentrically around the non-consumable electrode via the electrode centering member. The locking member is fitted across a first end on one side of the axial direction of the first member and a second end on the other side of the axial direction of the inner nozzle, and locks onto both the first member and the inner nozzle. With this configuration, some flexibility can be provided in the radial direction between the locking member and the first member or the inner nozzle. Therefore, for example, even if the non-consumable electrode is slightly bent due to manufacturing errors, the inner nozzle can be arranged concentrically around the non-consumable electrode.

Other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

1 is a schematic configuration diagram showing an example of a welding system including a welding torch according to the present invention. 1 is a perspective view showing an example of a welding torch according to the present invention. FIG. 3 is a plan view of the welding torch shown in FIG. 2 . FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 4 is a cross-sectional view taken along line VV in FIG. 3. FIG. 6 is an enlarged cross-sectional view taken along line VI-VI in FIG. 4. FIG. 7 is an enlarged cross-sectional view taken along line VII-VII in FIG. 4. 8 is an enlarged cross-sectional view taken along line VIII-VIII in FIG. 4. FIG. 5 is a partially enlarged view of FIG. 4 . FIG. 11 is a schematic configuration diagram showing another example of a welding system.

A preferred embodiment of the present invention will now be described in detail with reference to the drawings.

Figure 1 is a diagram showing a schematic configuration of a welding system equipped with a welding torch according to the present invention. Figure 2 is a perspective view showing an example of a welding torch according to the present invention. Figure 3 is a plan view of the welding torch shown in Figure 2. Figure 4 is a cross-sectional view taken along line IV-IV in Figure 3. Figure 5 is a cross-sectional view taken along line V-V in Figure 3. Figure 6 is an enlarged cross-sectional view taken along line VI-VI in Figure 4. Figure 7 is an enlarged cross-sectional view taken along line VII-VII in Figure 4. Figure 8 is an enlarged cross-sectional view taken along line VIII-VIII in Figure 4. Figure 9 is a partially enlarged view of Figure 4.

The welding system B1 shown in FIG. 1 is for performing welding on an object to be welded 9. The object to be welded 9 is a plate material made of metal. More specifically, the object to be welded 9 is a plate material made of a low melting metal such as a zinc-plated steel plate. The welding system B1 shown in FIG. 1 includes a robot 1, a welding torch A1, a power supply unit 4, a control unit 5, a gas supply source 6, a first gas adjustment unit 71, a second gas adjustment unit 72, and a gas pipe 8.

The robot 1 is equipped with a manipulator 11 and is, for example, an articulated robot. The welding torch A1 is supported by the manipulator 11. When the manipulator 11 is driven, the welding torch A1 can move freely up and down, forward and backward, and left and right.

The power supply unit 4 supplies power to the welding torch A1. The power supply unit 4 is connected to the workpiece 9. The gas supply source 6 supplies a predetermined welding gas to the welding torch A1. In this embodiment, the gas supply source 6 is a gas cylinder that stores an inert gas under high pressure. The type of inert gas stored in the gas supply source 6 is not particularly limited, and is, for example, at least one type of gas selected from argon (Ar) gas and helium (He) gas. In this embodiment, the inert gas stored in the gas supply source 6 is argon gas.

The gas pipe 8 is a gas flow path for sending an inert gas from the gas supply source 6 to the welding torch A1. In this embodiment, the gas pipe 8 includes a first gas pipe 81 and a second gas pipe 82 that extend in two branches. The first gas pipe 81 is a gas flow path for sending the first inert gas to the welding torch A1. The second gas pipe 82 is a gas flow path for sending the second inert gas to the welding torch A1.

The first gas adjustment unit 71 is provided in the first gas pipe 81 and includes, for example, a solenoid valve and a flow meter. In this embodiment, the opening of the solenoid valve is adjusted appropriately during welding work. In this embodiment, the flow rate of the inert gas supplied from the gas supply source 6 is adjusted by the first gas adjustment unit 71, and the inert gas is sent to the welding torch A1 as the first inert gas.

The second gas adjustment unit 72 is provided in the second gas pipe 82 and includes, for example, a solenoid valve and a flow meter. In this embodiment, the opening of the solenoid valve is adjusted appropriately during welding work. In this embodiment, the flow rate of the inert gas supplied from the gas supply source 6 is adjusted by the second gas adjustment unit 72 and sent to the welding torch A1 as the second inert gas.

The control unit 5 controls the voltage between the non-consumable electrode 25 and the workpiece 9, and the opening degree of the solenoid valves of the first gas adjustment unit 71 and the second gas adjustment unit 72. The control unit 5 separately controls the opening degree of the solenoid valve in the first gas adjustment unit 71 and the opening degree of the solenoid valve in the second gas adjustment unit 72.

As shown in Figures 2 to 9, the welding torch A1 is configured with a torch body 20, a non-consumable electrode 25, a rear collet 26, a rear collet body 27, a collet pressing member 28, a collet 29, a collet body 30, a block member 31, a cover 32, a lock nut 33, an insulating ring 34, an inner nozzle 35, an outer nozzle 36, a nozzle holder 37, a locking member 38, and an electrode centering member 39.

In this embodiment, the torch body 20 includes a block member 21 and cylindrical members 22 to 24. The cylindrical member 23 is disposed radially outward of the cylindrical member 22. The cylindrical member 24 is disposed radially outward of the cylindrical member 23. These cylindrical members 22 to 24 are disposed concentrically. The block member 21 supports the cylindrical members 22 to 24. In this embodiment, the block member 21 supports the cylindrical members 22 to 24 with the cylindrical member 22 inserted through it. The cylindrical members 22 to 24 are integrally connected to the block member 21 by an appropriate means such as brazing. The block member 21 is a member that receives power supply from the power supply unit 4 and is made of a conductive material. An example of the conductive material that constitutes the block member 21 is copper. The cylindrical members 22 to 24 are made of a conductive material. An example of the conductive material that constitutes the cylindrical members 22 to 24 is copper.

The non-consumable electrode 25 is a rod-shaped conductor extending along the axis CL. The non-consumable electrode 25 is made of, for example, tungsten. The non-consumable electrode 25 is connected to the power supply unit 4 via, for example, a conduit cable (not shown), and generates an arc between the non-consumable electrode 25 and the workpiece 9 when an arc voltage is applied between the non-consumable electrode 25 and the workpiece 9.

The non-consumable electrode 25 has an electrode main portion 251 and an electrode tapered portion 252. The electrode main portion 251 is a portion with a constant outer diameter and occupies most of the non-consumable electrode 25 except for the tip. The electrode main portion 251 is a portion formed in an approximately cylindrical shape so that the outer diameter is constant in design, and may include some manufacturing errors. The outer diameter of the electrode main portion 251 is not particularly limited, and in this embodiment, it is, for example, about 3.2 mm. The electrode tapered portion 252 is connected to the tip side of the non-consumable electrode 25 (one side in the direction of the axis CL) relative to the electrode main portion 251. The electrode tapered portion 252 has a diameter that decreases toward the tip side of the non-consumable electrode 25 (one side in the direction of the axis CL), and is approximately conical in shape.

The rear collet 26, rear collet body 27, collet pressing member 28, collet 29, and collet body 30 cooperate with each other to hold the non-consumable electrode 25. The rear collet 26, rear collet body 27, collet pressing member 28, collet 29, and collet body 30 are made of a conductive material. An example of the conductive material that constitutes the rear collet 26, rear collet body 27, collet pressing member 28, collet 29, and collet body 30 is copper.

The rear collet 26 and collet 29 surround the non-consumable electrode 25. The rear collet 26 is disposed near the base end of the non-consumable electrode 25 (the other side in the direction of the axis CL: the upper side in Figures 4 and 5). The collet 29 is disposed near the tip end of the non-consumable electrode 25 (one side in the direction of the axis CL: the lower side in Figures 4 and 5).

The rear collet body 27 is disposed radially outward of the rear collet 26. The rear collet body 27 is disposed radially inward of the cylindrical member 22. Although detailed illustrations are omitted, the rear collet body 27 has a screw portion that is screwed into the cylindrical member 22. A knob portion 271 is provided on the other side of the rear collet body 27 in the axial line CL direction (upper side in the drawings in Figures 4 and 5). By turning this knob portion 271, the position of the rear collet body 27 in the axial line CL direction relative to the cylindrical member 22 can be adjusted. One end of the rear collet body 27 in the axial line CL direction abuts against the other end of the collet 29 in the axial line CL direction. When the rear collet body 27 is moved to one side in the axial line CL direction, the collet 29 is pressed against one side of the axis CL. The collet body 30 is disposed radially outward of the collet 29. The collet body 30 is disposed on one side of the torch body 20 in the direction of the axis CL. The collet body 30 is disposed radially outside the non-consumable electrode 25 and is cylindrical. The other end of the collet body 30 in the direction of the axis CL is connected, for example, by threading, to one side of the cylindrical member 22 in the direction of the axis CL. In this way, the collet body 30 is supported by the torch body 20 (cylindrical member 22).

The collet holding member 28 is disposed radially inside the rear collet body 27. Although detailed illustrations are omitted, the collet holding member 28 has a screw portion that is screwed into the rear collet body 27. A knob 281 is provided on the other side in the direction of the axis CL of the collet holding member 28 (the upper side in the drawings in Figures 4 and 5). By turning this knob 281, the position of the collet holding member 28 in the direction of the axis CL relative to the rear collet body 27 can be adjusted. One end of the collet holding member 28 in the direction of the axis CL abuts against the other end of the rear collet 26 in the direction of the axis CL. When the collet holding member 28 is moved to one side in the direction of the axis CL, the rear collet 26 is pressed against one side of the axis CL.

The rear collet 26 and the collet 29 each have a plurality of slits formed at the tip side (one side in the direction of the axis CL: the lower side in Figures 4 and 5) that extend in the direction of the axis CL, and each have a plurality of movable pieces 261, 291 located between adjacent slits. As described above, when the rear collet body 27 is moved to one side in the direction of the axis CL, the collet 29 is pressed against one side of the axis CL. Then, the plurality of movable pieces 291 at the tip of the collet 29 are pressed against the tip of the collet body 30 and contract in diameter, and the collet 29 holds the non-consumable electrode 25 between them. Also, as described above, when the collet pressing member 28 is moved to one side in the direction of the axis CL, the rear collet 26 is pressed against one side of the axis CL. Then, the multiple movable pieces 261 at the tip of the rear collet 26 are pressed against the inner periphery of the tip of the rear collet body 27, reducing its diameter, and the rear collet 26 clamps and holds the non-consumable electrode 25. In this way, the rear collet 26, rear collet body 27, collet pressing member 28, collet 29, and collet body 30 work together to firmly hold the non-consumable electrode 25.

The cover 32 is a cylindrical member made of an insulating material and covers the cylindrical member 24. The lock nut 33 is threadedly connected to the lower end of the cylindrical member 24 (the lower end in Figures 4 and 5) and abuts against the lower end of the cover 32.

As shown in Figures 4 and 5, the inner nozzle 35 is disposed around the tip of the non-consumable electrode 25 (one side in the direction of the axis CL). The inner nozzle 35 is disposed on the lower side (one side in the direction of the axis CL) of the collet body 30. The inner nozzle 35 is substantially cylindrical, and is disposed radially outward of the non-consumable electrode 25 (electrode main portion 251). In this embodiment, an electrode centering member 39 is interposed between the inner nozzle 35 and the non-consumable electrode 25.

The locking member 38 is fitted over both the collet body 30 and the inner nozzle 35. More specifically, the locking member 38 is fitted over the lower end (one end in the direction of the axis CL) of the collet body 30 and the upper end (the other end in the direction of the axis CL) of the inner nozzle 35. The locking member 38 has a female threaded portion 381 and a tip cylindrical portion 382. The female threaded portion 381 is formed on the inner circumference of the upper end side of the locking member 38. The tip cylindrical portion 382 is provided on the lower end side of the locking member 38. The tip cylindrical portion 382 is a cylindrical portion having a smaller diameter than other portions. The step portion 383 is provided in the center of the locking member 38 in the direction of the axis CL. In the illustrated example, the locking member 38 has a cap nut structure.

In this embodiment, as shown in Figs. 4, 5, and 9, the locking member 38 and the lower end of the collet body 30 are screwed together. For example, a male thread 301 is formed on the outer periphery of the lower end of the collet body 30, and the female thread 381 of the locking member 38 is screwed into the male thread 301 of the collet body 30. Meanwhile, the tip cylindrical portion 382 of the locking member 38 is fitted onto the inside nozzle 35, and the step portion 383 of the locking member 38 is locked by a flange portion 351 provided on the outer periphery of the other end of the inner nozzle 35 in the axial line CL direction. This limits the relative movement of the inner nozzle 35 and the locking member 38 in the axial line CL direction. The collet body 30 configured as described above corresponds to an example of the "first member" of the present invention.

The electrode centering member 39 is roughly cylindrical and is disposed radially outside the non-consumable electrode 25 and radially inside the inner nozzle 35. A recess 353 is formed on the inner circumference of the inner nozzle 35 on the other side of the axis CL direction, and a part of the electrode centering member 39 is fitted into this recess 353. The inner diameter dimension of the electrode centering member 39 is slightly larger than the outer diameter dimension of the non-consumable electrode 25 (electrode main part 251). As a result, the electrode centering member 39 is fitted concentrically around the non-consumable electrode 25. In addition, the inner diameter dimension of the inner nozzle 35 (recess 353) is slightly larger than the outer diameter dimension of the electrode centering member 39. As a result, the inner nozzle 35 is fitted concentrically around the electrode centering member 39. Therefore, the inner nozzle 35 is arranged concentrically around the non-consumable electrode 25 via the electrode centering member 39. As shown in FIG. 8, multiple grooves 391 are formed in the inner periphery of the electrode core member 39. These grooves 391 are provided at regular intervals in the circumferential direction of the electrode core member 39. A gap is formed between the non-consumable electrode 25 and the portion where the grooves 391 are formed, and this gap constitutes the first gas flow path G1 described below.

In this embodiment, the tip of the non-consumable electrode 25 coincides with the tip of the inner nozzle 35 in the direction of the axis CL, or protrudes slightly from the tip of the inner nozzle 35 to one side in the direction of the axis CL. The protruding length P1 by which the tip of the non-consumable electrode 25 protrudes from the tip of the inner nozzle 35 to one side in the direction of the axis CL is, for example, in the range of 0 to 2 mm.

The nozzle holder 37 is cylindrical. The nozzle holder 37 is integrally connected to the outer periphery of the middle part of the collet body 30 in the direction of the axis CL by means of, for example, brazing.

As shown in Figures 4 and 5, the outer nozzle 36 is disposed radially outward of the inner nozzle 35. In the illustrated example, the outer nozzle 36 is generally cylindrical, with the tip side (one side in the direction of the axis CL) having a smaller diameter than the other portions. In this embodiment, the outer nozzle 36 is disposed concentrically with the non-consumable electrode 25 and the inner nozzle 35. The outer nozzle 36 is attached to the outer periphery of the nozzle holder 37 by a screw connection.

As shown in Figures 4, 9, etc., in this embodiment, the tip of the inner nozzle 35 protrudes from the tip of the outer nozzle 36 to one side in the direction of the axis CL. The protruding length P2 by which the tip of the inner nozzle 35 protrudes from the tip of the outer nozzle 36 to one side in the direction of the axis CL is, for example, in the range of 0 to 5 mm.

The insulating ring 34 is a cylindrical member made of an insulating material. The insulating ring 34 is interposed between the lock nut 33 and the outer nozzle 36 in the direction of the axis CL.

As shown in Figures 4 to 9, in this embodiment, the welding torch A1 is formed with a first gas flow path G1, a second gas flow path G2, and a cooling water flow path W.

The first gas flow passage G1 is a flow passage for flowing the first inert gas. In Figures 4, 5, and 9, the flow of the first inert gas in the first gas flow passage G1 is indicated by two-dot chain arrows. The first gas flow passage G1 is formed between the rear collet body 27 and the cylindrical member 22, between the collet 29 and the collet body 30, between the non-consumable electrode 25 (electrode main part 251) and the collet 29, between the non-consumable electrode 25 (electrode main part 251) and the collet body 30, between the non-consumable electrode 25 (electrode main part 251) and the electrode centering member 39, and between the non-consumable electrode 25 (electrode main part 251) and the inner nozzle 35.

In this embodiment, as shown in FIG. 5, a first gas inlet 221 for introducing a first inert gas is provided at the upper end of the cylindrical member 22. The first gas inlet 221 is connected to the first gas flow path G1. When the first inert gas is introduced from the first gas inlet 221, the first inert gas flows from the other side to one side in the direction of the axis CL in the first gas flow path G1, passes between the non-consumable electrode 25 (electrode main part 251) and the inner nozzle 35, and then is ejected from the opening 352 at the tip of the inner nozzle 35.

The second gas flow path G2 is a flow path for flowing the second inert gas. In Figs. 4, 5, and 9, the flow of the second inert gas in the second gas flow path G2 is indicated by dotted arrows. The second gas flow path G2 is formed between the cylindrical member 23 and the cylindrical member 24, between the cylindrical member 22 and the cylindrical member 24, between the collet body 30 and the cylindrical member 22, between the collet body 30 and the insulating ring 34, between the nozzle holder 37, between the locking member 38 and the outer nozzle 36, and between the inner nozzle 35 and the outer nozzle 36. In this embodiment, as shown in Figs. 4 and 7, a plurality of communication holes 222 are formed at the lower end of the cylindrical member 22, penetrating the cylindrical member 22 in the thickness direction. The plurality of communication holes 222 are evenly distributed in the circumferential direction of the cylindrical member 22. In the second gas flow path G2, communication is provided between the cylindrical member 22 and the cylindrical member 24, and between the collet body 30 and the cylindrical member 22, via multiple communication holes 222.

In this embodiment, as shown in FIG. 5, the torch body 20 (block member 21) is provided with a second gas inlet 211 for introducing a second inert gas. The second gas inlet 211 is connected to the second gas flow passage G2. When the second inert gas is introduced from the second gas inlet 211, the second inert gas flows from the other side to one side in the direction of the axis CL in the second gas flow passage G2, passes between the inner nozzle 35 and the outer nozzle 36, and is then ejected from the opening 362 at the tip of the outer nozzle 36.

The cooling water flow path W is a flow path for passing the cooling water. In FIG. 4, the flow of the cooling water in the cooling water flow path W is indicated by solid arrows. The cooling water flow path W is formed mainly between the cylindrical member 22 and the cylindrical member 23. The cooling water flow path W includes a water supply side flow path W1 and a condensation side flow path W2. Although detailed illustrations are omitted, when the cooling water is introduced from a cooling water inlet provided at an appropriate position in the block member 21, the cooling water flows from the other side to one side in the axis CL direction in the water supply side flow path W1. The cooling water then turns around near the lower end of the cylindrical member 23 and flows from one side to the other side in the axis CL direction in the condensation side flow path W2, and is discharged from a cooling water outlet provided in the block member 21.

In this embodiment, the flow rate of the first inert gas introduced into the first gas inlet 221 is adjusted by the first gas adjustment unit 71 (see FIG. 1) described above. The first gas adjustment unit 71 is interposed between the gas supply source 6 and the first gas flow path G1. The amount of the first inert gas flowing through the first gas flow path G1 is adjusted as desired by the first gas adjustment unit 71.

In this embodiment, the flow rate of the first inert gas introduced into the first gas inlet 221 is adjusted by adjusting the flow rate of the first inert gas flowing through the first gas piping 81 in the first gas adjustment unit 71. The configuration of the first gas adjustment unit 71 is not limited to this, and the flow rate of the first inert gas introduced into the first gas inlet 221 may be adjusted, for example, by adjusting the gas pressure or flow rate of the first inert gas in the first gas adjustment unit 71. Therefore, even when the gas pressure or flow rate of the first inert gas is adjusted in the first gas adjustment unit 71, this is included in the "adjusting the flow rate of the first inert gas introduced into the first gas inlet (221)" of the present invention.

In this embodiment, the flow rate of the second inert gas introduced into the second gas inlet 211 is adjusted by the second gas adjustment unit 72 (see FIG. 1). The second gas adjustment unit 72 is interposed between the gas supply source 6 and the second gas flow path G2. The amount of the second inert gas flowing through the second gas flow path G2 is adjusted as desired by the second gas adjustment unit 72. Therefore, the flow rate of the first inert gas introduced into the first gas inlet 221 and the flow rate of the second inert gas introduced into the second gas inlet 211 can be adjusted individually. The flow rate of the first inert gas introduced into the first gas inlet 221 and the flow rate of the second inert gas introduced into the second gas inlet 211 are not particularly limited. An example of the flow rate of the first inert gas introduced into the first gas inlet 221 is about 5 to 12 L/min. An example of the flow rate of the second inert gas introduced into the second gas inlet 211 is about 5 to 15 L/min.

In this embodiment, the flow rate of the second inert gas introduced into the second gas inlet 211 is adjusted by adjusting the flow rate of the second inert gas flowing through the second gas piping 82 in the second gas adjustment unit 72. The configuration of the second gas adjustment unit 72 is not limited to this, and the flow rate of the second inert gas introduced into the second gas inlet 211 may be adjusted, for example, by adjusting the gas pressure or flow rate of the second inert gas in the second gas adjustment unit 72. Therefore, even when the gas pressure or flow rate of the second inert gas is adjusted in the second gas adjustment unit 72, this is included in the "adjusting the flow rate of the second inert gas introduced into the second gas inlet (211)" of the present invention.

As shown in FIG. 9, the gap between the non-consumable electrode 25 (electrode main part 251) and the inner nozzle 35 in the first gas flow path G1 is smaller than the gap between the inner nozzle 35 and the outer nozzle 36 in the second gas flow path G2. In the first gas flow path G1, the minimum gap (first minimum gap L1) between the non-consumable electrode 25 (electrode main part 251) and the inner nozzle 35 is, for example, about 0.5 to 1.5 mm. In the second gas flow path G2, the minimum gap (second minimum gap L2) between the inner nozzle 35 and the outer nozzle 36 is, for example, about 2 to 5 mm. Regarding the ratio of the first minimum gap L1 to the second minimum gap L2, the first minimum gap L1 is, for example, 0.2 to 0.5 times the second minimum gap L2, and preferably 0.2 to 0.3 times the second minimum gap L2. In addition, the flow rate of the first inert gas flowing through the first minimum gap L1 of the first gas flow path G1 is, for example, about 8 to 18 m/sec.

Next, the operation of this embodiment will be explained.

The welding torch A1 of this embodiment includes a non-consumable electrode 25 extending in the direction of the axis CL, an inner nozzle 35, and an outer nozzle 36. The inner nozzle 35 is arranged concentrically around the non-consumable electrode 25, and a first gas flow path G1 for flowing a first inert gas is formed between the non-consumable electrode 25 and the inner nozzle 35. The outer nozzle 36 is arranged radially outside the inner nozzle 35, and a second gas flow path G2 for flowing a second inert gas is formed between the inner nozzle 35 and the outer nozzle 36. With this configuration, during welding, the first inert gas that flows through the first gas flow path G1 and is ejected from the tip of the inner nozzle 35 functions as a plasma gas, and the second inert gas that flows through the second gas flow path G2 and is ejected from the tip of the outer nozzle 36 functions as a shielding gas. As a result, the arc generated between the workpiece 9 and the tip of the non-consumable electrode 25 is narrowed, and welding can be performed efficiently using an arc (plasma arc) with high energy density.

The welding torch A1 includes an electrode centering member 39 and a locking member 38. The electrode centering member 39 is fitted concentrically around the non-consumable electrode 25. The inner nozzle 35 is also fitted concentrically around the electrode centering member 39. As a result, the inner nozzle 35 is arranged concentrically around the non-consumable electrode 25 via the electrode centering member 39.

The locking member 38 is fitted across the lower end (first end on one side in the direction of the axis CL) of the collet body 30 (first member) and the upper end (second end on the other side in the direction of the axis CL) of the inner nozzle 35, and locks onto both the collet body 30 and the inner nozzle 35. This configuration allows some radial flexibility between the locking member 38 and the collet body 30 or the inner nozzle 35. Therefore, for example, even if the non-consumable electrode 25 is slightly bent due to manufacturing errors, the inner nozzle 35 can be arranged concentrically with the non-consumable electrode 25.

If the inner nozzle 35 becomes misaligned with respect to the non-consumable electrode 25, the first inert gas (plasma gas) ejected from the opening 352 at the tip of the inner nozzle 35 will drift. The minimum gap (first minimum gap L1) between the non-consumable electrode 25 (electrode main portion 251) and the inner nozzle 35 that constitute the first gas flow path G1 is narrow, and if the inner nozzle 35 becomes misaligned, the first inert gas (plasma gas) will drift. However, as described above, the structure that includes the electrode centering member 39 and the locking member 38 ensures that the inner nozzle 35 is positioned concentrically with the non-consumable electrode 25. This is suitable for improving welding quality.

The locking member 38 and the lower end of the collet body 30 (the first end on one side in the direction of the axis CL) are screw-connected. This configuration allows for a suitable degree of dimensional flexibility between the locking member 38 and the collet body 30 with a relatively simple structure. In addition, when replacing the inner nozzle 35, the inner nozzle 35 can be easily removed by loosening the female thread portion 381 of the locking member 38, making replacement of the inner nozzle 35 easy.

In addition, since the inner nozzle 35 is arranged concentrically radially outside the non-consumable electrode 25, the first inert gas flowing through the first gas flow passage G1 between the non-consumable electrode 25 and the inner nozzle 35 becomes a substantially uniform and relatively high-speed airflow around the non-consumable electrode 25 and is ejected from the opening 352 at the tip of the inner nozzle 35. As a result, even when welding a workpiece 9 made of a low-melting metal such as a zinc-plated steel sheet, fumes and the like generated during welding are blown away by the high-speed airflow of the first inert gas flowing around the non-consumable electrode 25. Therefore, it is possible to prevent fumes and the like from adhering to the tip of the non-consumable electrode 25 or the tip of the inner nozzle 35.

Furthermore, the tip of the non-consumable electrode 25 coincides with the tip of the inner nozzle 35 in the axial line CL direction, or protrudes slightly from the tip of the inner nozzle 35 to one side in the axial line CL direction. The protruding length P1 by which the tip of the non-consumable electrode 25 protrudes from the tip of the inner nozzle 35 to one side in the axial line CL direction is in the range of 0 to 2 mm. With such a tip position of the non-consumable electrode 25, the gap between the non-consumable electrode 25 and the inner nozzle 35 is kept approximately constant and narrow in the range from the middle of the axial line CL direction of the inner nozzle 35 to the vicinity of the tip. Therefore, the high-speed airflow of the first inert gas flowing around the non-consumable electrode 25 is ejected from the opening 352 at the tip of the inner nozzle 35 with almost no decrease in flow rate. This is preferable in terms of preventing the adhesion of fumes, etc. to the tip of the non-consumable electrode 25 and the tip of the inner nozzle 35. In addition, the above-mentioned effects are achieved by devising the shape and arrangement of the inner nozzle 35, making it possible to relatively simplify the structure of the welding torch A1 and to miniaturize the tip of the welding torch A1.

The welding torch A1 has a first gas inlet 221 that leads to the first gas flow passage G1 and a second gas inlet 211 that leads to the second gas flow passage G2. The flow rate of the first inert gas introduced into the first gas inlet 221 and the flow rate of the second inert gas introduced into the second gas inlet 211 are adjusted individually. With this configuration, even when the flow rate of the second inert gas (shielding gas) is adjusted to increase or decrease, the flow rate of the first inert gas (plasma gas) does not change unintentionally, and it is possible to set the flow rate of the first inert gas to a preferred value. Conversely, even when the flow rate of the first inert gas (plasma gas) is adjusted, the flow rate of the second inert gas (shielding gas) does not change. That is, according to the welding torch A1 and the welding system B1, it is possible to supply a desired amount of the first inert gas (plasma gas) between the non-consumable electrode 25 and the workpiece 9, and it is also possible to supply a sufficient amount of the second inert gas (shielding gas). The supply amount of the first inert gas (plasma gas) can be set as intended, making it easier to control the arc (plasma arc) that occurs between the workpiece 9 and the non-consumable electrode 25.

The gases (first inert gas and second inert gas) supplied to the welding torch A1 are at least one type of gas selected from argon gas and helium gas. With such a configuration in which only limited types of inert gas are supplied to the welding torch A1, the handling and management of the welding gas is easy. Furthermore, when the first inert gas and the second inert gas are the same type of gas (argon gas) as in this embodiment, the welding system B1 only needs to be provided with a single gas supply source 6 as a supply source of the first inert gas and the second inert gas. Therefore, the management of the gases (first inert gas and second inert gas) supplied to the welding torch A1 is easier, and the configuration of the welding system B1 is simplified.

In the welding torch A1, the minimum gap (first minimum gap L1) between the non-consumable electrode 25 (electrode main part 251) and the inner nozzle 35 in the first gas flow path G1 is 0.2 to 0.5 times the minimum gap (second minimum gap L2) between the inner nozzle 35 and the outer nozzle 36 in the second gas flow path G2. By making the ratio of the first minimum gap L1 to the second minimum gap L2 small in this way, it is possible to efficiently increase the flow rate of the first inert gas flowing between the non-consumable electrode 25 and the inner nozzle 35. Therefore, adhesion of fumes and the like to the tip of the non-consumable electrode 25 and the tip of the inner nozzle 35 is appropriately prevented, and the arc (plasma arc) generated between the workpiece 9 and the non-consumable electrode 25 is constricted, and the concentration of the arc is further increased.

FIG. 10 shows another example of the welding system according to the present invention. In the welding system B2 shown in FIG. 10, the supply mode of the first inert gas and the second inert gas is different from that of the welding system B1 of the above embodiment. In the welding system B2, a first gas supply source 61 and a second gas supply source 62 are provided instead of the gas supply source 6 of the above embodiment. The first gas supply source 61 is a gas cylinder that stores the first inert gas in a high-pressure state. The second gas supply source 62 is a gas cylinder that stores a second inert gas different from the first inert gas in a high-pressure state. The gas species of the first inert gas stored in the first gas supply source 61 and the second inert gas stored in the second gas supply source 62 are not particularly limited. The first inert gas in the first gas supply source 61 is, for example, argon gas. The second inert gas in the second gas supply source 62 is, for example, any one of argon gas, helium gas, and nitrogen (N ₂ ) gas, or a mixture gas thereof.

The first gas supply source 61 is connected to a first gas pipe 81, and the first gas adjustment unit 71 is provided on the first gas pipe 81. The flow rate of the first inert gas supplied from the first gas supply source 61 is adjusted by the first gas adjustment unit 71 and sent to the welding torch A1. The second gas supply source 62 is connected to a second gas pipe 82, and the second gas adjustment unit 72 is provided on the second gas pipe 82. The flow rate of the second inert gas supplied from the second gas supply source 62 is adjusted by the second gas adjustment unit 72 and sent to the welding torch A1. The welding system B2 shown in FIG. 10 has the same effects as the above embodiment within the same range of configuration as the welding torch A1 and the welding system B1 of the above embodiment.

Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to the above-mentioned embodiments, and all modifications within the scope of the matters described in each claim are included in the scope of the present invention.

In the above embodiment of the welding torch A1, the outer nozzle 36 is arranged concentrically with the inner nozzle 35, but the present invention is not limited to this. The outer nozzle 36 may be arranged offset radially from the inner nozzle 35. In addition, the second gas inlet for introducing the second inert gas may be provided on the side of the outer nozzle 36.

A1: welding torch, 211: second gas inlet, 221: first gas inlet, 25: non-consumable electrode, 30: collet body (first member), 35: inner nozzle, 36: outer nozzle, 38: locking member, 39: electrode centering member, G1: first gas flow path, G2: second gas flow path, CL: axis, P1: protrusion length, L1: first minimum gap, L2: second minimum gap

Claims (5)

a non-consumable electrode extending in an axial direction;
a cylindrical first member disposed radially outward of the non-consumable electrode;
an inner nozzle disposed radially outward of the non-consumable electrode and on one side of the first member in the axial direction;
a locking member that is fitted across a first end portion of the first member on one side in the axial direction and a second end portion of the inner nozzle on the other side in the axial direction and that is locked to both the first member and the inner nozzle;
an outer nozzle disposed radially outside the inner nozzle;
an electrode centering member disposed radially outward of the non-consumable electrode and radially inward of the inner nozzle,
the electrode centering member is concentrically fitted around the non-consumable electrode, and the inner nozzle is concentrically fitted around the electrode centering member;
a first gas flow passage for flowing a first inert gas is formed between the non-consumable electrode and the inner nozzle;
A welding torch, wherein a second gas flow passage for flowing a second inert gas is formed between the inner nozzle and the outer nozzle. The welding torch of claim 1, wherein the locking member and the first end of the first member are connected by a screw thread. a first gas inlet communicating with the first gas flow passage and a second gas inlet communicating with the second gas flow passage;
3. The welding torch according to claim 1, wherein a flow rate of the first inert gas introduced into the first gas inlet and a flow rate of the second inert gas introduced into the second gas inlet are each adjusted independently. The welding torch of claim 3, wherein the first inert gas and the second inert gas are both at least one gas selected from argon gas and helium gas. A welding torch according to any one of claims 1 to 4, wherein a first minimum gap, which is the minimum gap between the non-consumable electrode and the inner nozzle in the first gas flow path, is 0.2 to 0.5 times a second minimum gap, which is the minimum gap between the inner nozzle and the outer nozzle in the second gas flow path.

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